Water service pipe is a path along which water is supplied and, for example, in water supply system, the pipe is connected from purification plant to home and water is supplied to the home along the pipe.
Generally, water which flows along the pipe contains impurities such as rust from the pipe, and the water discharged from the pipe when water-valve is just open contains the most amount of the impurities, and the amount of the impurities of the discharged water from the pipe reduces as the opening-hour of the water-valve becomes longer. This is because the impurities such as the rust on the pipes are washed out as the water flows out.
Accordingly, the amount of the impurities of the discharged water reduces as time goes on after the open of the water-valve and, generally, the amount of the impurities of the discharged water becomes the lowest when the water-valve is closed and the water-supply is terminated. That is, unless the event such as inflow of foreign substances happens, the discharged water contains the lowest impurities when the water-supply is terminated.
When the use of the water is resumed after the use of the water started by opening the water-valve is completed by closing the water-valve, the impurities such as the rust generated during the close of the water-valve are discharged along with the water at the initial time and, if the use of the water is kept after the all-exhaustion of the impurities generated during the close of the water-valve, the amount of the impurities of the water reduces furthermore and becomes smaller than the lowest amount of the impurities in the former use over some time.
Accordingly, along the time of the use of the water until present time, a point of the lowest amount of the impurities that the discharged water contains exists and this becomes optimum amount of the impurities until the present use in connection with the water service pipe. That is, the water at the point contains the lowest impurities among the discharged water from the water service pipe until now.
There is a desire to use water having optimum quality (that is, the amount of the impurities in the water is the lowest until the present use), for example, a user wants to drink the water having the optimum quality. The present invention satisfies this demand.